Absorbent articles such as diapers, adult incontinence garments, feminine care products, child training pants, pull-ups, bandages, gloves and similar products that directly contact skin are well known. A disposable absorbent article is typically composed of a top layer that is adjacent to a user""s body and a back layer that faces the clothing of the user. An absorbent material is located between the top layer and the bottom layer. The top layer permits a liquid from the user to move through the top layer toward the back layer. The back layer does not allow liquid to be transferred from the inside of the absorbent article onto the user""s clothing. The absorbent material absorbs the liquid and keeps the skin dry.
During normal operation after a fluid is discharged from a user, the fluid will flow through the top layer and be absorbed by the absorbent material. The absorbent material is designed to absorb, redistribute, and store the fluid until the absorbent article is discarded. In some instances, however, fluid may return from the absorbent material to once again contact the user""s skin. Fluid return can occur, for example, if the absorbent material cannot sufficiently absorb the fluid due to the composition of the absorbent material. Unabsorbed liquid undesirably results in over-hydration of the contacted skin and in turn, increases a chance of skin irritation to the user. In addition to being an irritant, excessive moisture on the user""s skin can cause, among other things, the growth of microorganisms that can lead to the onset of rashes or infection.
Various tests exist for measuring performance and suitability of absorbent materials to prevent the foregoing problems. Known tests include capacitance, conductance, electrical impedance, and/or evaporative or Trans-Epidermal Water Loss (TEWL) evaluations. Typically, these tests measure fluid absorbency, fluid leakage, and other criteria of the materials for use in absorbent articles.
One such test is the Adult Forearm Test or xe2x80x9carmbandxe2x80x9d test, which is conventionally used to evaluate the effectiveness of disposable diapers to keep the skin dry. One variation of the armband test uses pre-loaded patches from diapers placed on an adult volar forearm. Changes in skin surface hydration are measured by evaporimetry or TEWL evaluation. Differences in skin surface hydration between cloth diapers and disposable paper diapers have been noted using this armband test variant.
Another armband test uses an intact diaper wrapped around the forearm. Physiological saline is injected into the diaper at a rate and volume that represent normal urination by a child. Post-occlusion measurements are made after one hour, and measurements of skin hydration are made by computerized evaporimetry or by electrical conductance.
In general, the present invention provides an evaluation apparatus to evaluate materials quickly, efficiently and cost effectively. The evaluation apparatus acts as a pre-screening tool to bench test materials for diaper, childcare, feminine care, adult care, health care, competitive and other products without human subjects. The component parts of the invention are simple, reliable, and economical to manufacture and use. Also, used herein, the terms xe2x80x9csimulated,xe2x80x9d xe2x80x9cvirtual,xe2x80x9d xe2x80x9cartificial,xe2x80x9d xe2x80x9csyntheticxe2x80x9d and like terms are used interchangeably to indicate manufactured materials or objects, and in the case of substrates, dissected or bioengineered skin samples, unless otherwise indicated.
In one aspect of the invention, a heated mechanical arm includes a Plexiglas(copyright)-type cylinder, which simulates an adult forearm. The heated mechanical arm is designed to rapidly pre-screen and rank a material for further evaluation, possibly on human subjects. The heated mechanical arm further includes a fluid injection port and incorporates a heater element or a flexible heater. The flexible heater is made, for instance, from rubber silicone and can be wrapped about the mechanical arm. The heater includes a heater hole that complements the fluid injection port of the mechanical arm to simulate a sweat gland, pore, a urethra and the like.
Also in the foregoing aspect, a simulated skin substrate is placed on or near the heater. The heater heats the simulated skin to emulate normal human skin temperature. The material is wrapped about the skin and heater and insulted with saline or other simulated physiological fluid via the fluid injection port, either automatically or manually by a fluid loading device. At a predetermined time, the material is removed and the simulated skin is evaluated for dryness.
Thus, the present invention enables rapid pre-screening of materials by using economical artificial components and avoiding variables in a population of human subjects. Other aspects and advantages of the invention will be apparent from the following description and the attached drawings, or can be learned through practice of the invention.